Mechanical spring constant load device

ABSTRACT

A spring member having conically extending resilient fingers which bear against a disc provides a constant load to a shaft coupled to the disc in the presence of movement of the shaft from a fixed axial position. The constant load device can be used in many mechanical applications such as an automobile chassis spring or a spring for a friction clutch. The constant load device can also be used in electronic applications, such as for holding a vidicon in assembled position with an electron intensifier.

United StateS Patent n 1 Nation MECHANICAL SPRING CONSTANT LOAD DEVICEMelvin s. Nation, Bensenville, Ill. Assignee: Motorola, Inc., FranklinPark, Ill.

Filed: April 26, 1971 Appl. No.: 137,285

[75] Inventor: 73]

US. Cl. ..267/l6l, l78/7.8, 192/89 Int. Cl. ..Fl6f I/34 Field of Search.....267/l6l, 47; 192/89; l78/7.8

[56] References Cited UNITED STATES PATENTS 3,235,049 2/1966 Hufstaderu..l92/89 Jan. 23, 1973 Primary Examiner-James B. Marbert AssistantExaminer-Richard A. Bertsch Attorney-Mueller & Aichele 57 ABSTRACT Aspring member having conically extending resilient fingers which bearagainst a disc provides a constant load to a shaft coupled to the discin the presence of movement of the shaft from a fixed axial position.The constant load device can be used in many mechanical applicationssuch as an automobile chassis spring or a spring for a friction clutch.The constant load device can also be used in electronic applications,such as for holding a vidicon in assembled position with an electronintensifier.

9 Claims, 4 Drawing Figures PATENTEBJAN 23 ms 3.712.604

15 FIG. 1

22 4 42 FIG. 3

O 50 FIG 2 L 6 4 L. Z;\ 43 20 35 FIG. 4

INVENTOR MELVIN S. NATION 73 MZW ATTYS.

MECHANICALSPRING CONSTANT LOAD DEVICE BACKGROUND OF THE INVENTION Thereare many applications in which it is desired to provide constant load orpressure on a shaft to hold the same in given position, to support adevice, and/or to provide shock absorbing action. A problem is presentedwherein such load is to be applied to a shaft which is not always in thesame axial position in that the load applied may be varied as the axialposition of the shaft changes. Many spring structures cannot be used inapplications where changes in the axial position of the shaft takeplace.

SUMMARY or THE INVENTION It is, therefore, an object of the presentinvention to provide a device for applying a constant load to a shaft,which is of simple and inexpensive construction.

Another object of the invention is to provide a constant load device fora shaft which maintains a constant pressure thereto throughout a rangeof center axis displacements. I v

A feature of the invention is the provision of a constant load deviceincluding a conical cantilever beam spring which cooperates with thecircular edge of a button or plate coupled to a shaft to provide a loadon the shaft, with the load remaining substantially constant in thepresence of lateral movement or the button attendant to displacement ofthe axis of the shaft. The button may be made of plastic material andhave some resiliency, and the conical cantilever beam spring may includeaplurality of conically positioned resilient fingers which extend at anangle with respect to the plastic button.

I Another feature of the invention is the provision of a constant loaddevice which is adapted to hold an electron device, such as a vidicon,in optical face contact with another device, such as an imageintensifier, and which includes a button coupled to the end of the neckof the vidicon and having a load applied thereto by a conical springstructure. The spring structure has a plurality of resilient fingersengaging the edge of the button and applying a substantially constantload thereto as the position of the button changes because of a shift ofthe center axis of the vidicon tube.

BRIEF DESCRIPTIONOF THE DRAWINGS FIG. lis a schematic illustration ofthe constant load device on the invention; i

FIG. 2illustrates a, friction clutch utilizing the constant load'deviceof the'invention;

FIG. 3 illustrates a front suspension for an automobile utilizing theload device of the invention; and

. FIG. 4 shows a vidicon tube held against an image intensifier by meansof the constant load device of the invention. .w

DESCRIPTIONOF THE PREFERRED I EMBODIMENTS In FIG. 1 there is illustrateda shaft having an axis shown in its center position, with axialpositions to which the shaft may move shown by dot-dash lines. Connectedto one end of the shaft is a plate or button 12 having a circular edge.The circular edge of the button engages fingers of a conical cantileverbeam spring structure 14 having an outer edge which may be supported inany suitable manner. The spring structure 14 may be constructed of ametal such as beryllium copper. The spring fingers 15 individually bearagainst the circular edge of the button 12 to provide a loading on theshaft 10. The button can be constructed of a plastic materialhaving someresilience, such as the acetal resin material known as DELRIN, made byE.I. DuPont de Nemours and Company, Wilmington, Del. As indicated by thedot-dash line, the shaft can move through a limited angle from itscenter axis. This will cause the plane of the plate 12 to change.However, the

engagement of the fingers 15 against the edge of the plate 12 willresult in a substantially constant load on the shaft 10 as the shaftmoves through this limited angular range.

FIG. 2 illustrates the use of the constant load device of the inventionin a friction clutch. The clutch couples an axle or drive shaft to agear 22.'The shaft 20 has a 22, and is of generally the sameconfiguration as the spring 14 of FIG. I. An annular disc or buttonbears against the fingers of the spring 28, in the same mannerillustrated in FIG. 1. The disc 30 is supported by bearing 32 supportedon the shaft 20. j

The spring 28 bears against the disc 30 to hold the annular frictionengaging surfaces of the parts 21- and 23 in engagement, so that thegear 22 moves with the shaft 20. To disengage the clutch, pivoted armengages rim 36 on the shaft 20 to pull the shaft axially in thedirection to move the flange 21 away from the projecting surface 23.This removes the driving connection between the shaft 20 and the gear23. To do this, the plate 30 causes the fingers of spring 28 to flex.The bearings 26 and 32 permit the shaftto rotate 20 with respect to theend plate '24 connected to thegear 22 and with respect to the plate 30,when the clutch is disengaged by action of the pivoted arm 35. When theaxial force on the shaft'20'is released, the fingers of the string 28bearing against the plate 30 will pull shaft 20 in the direction tocause the flange 21 to engage the projecting surface 23 on the gear 22,so that movement of the shaft 20 will drive the gear 22. FIG. 3 showsanother application in which the constant load device can be used. Thisshows the front suspension of an automobile which has a chassis 40supporting an engine 42.- A wheel 44 is connected to the chassis byupper and lower driving arms 46 and 47. A shock absorber 43 may beconnected between the lower driving arm 47 and the chassis 40. The wheel44 is rotatable on an axle which is secured to the upper and lowerdriving arms by structure which is well known and not shown. Provisionsfor steering can also be connected to the axle 45.

The chassis 40 has a bracket 48 which supports the edge of the conicalcantilever beam spring 50, which is similar to the spring l4 of FIG. 1.Engaging the fingers of the spring 50 is disc 52, which is secured toshaft 54. The lower end of the shaft 54 is conducted to the upperdriving arm 46. Accordingly, the weight of the chassis applied to theedge of the conical spring 50 causes the spring to apply pressure to thedisc 52. The spring 50 and the disc 52, which can have some resilience,therefore form a spring support for the chassis. In this construction,it will be apparent that as the upper and lower driving arms move, theposition of the axis of shaft 54 will change so that the disc 52 willshift with respect to the conical fingers of spring 50. This however,will not result in a substantial change in the spring pressure whichsupports the chassis.

FIG. 4 illustrates the application of the invention to a structure forsupporting a vidicon tube to an image intensifier unit. The structureincludes a tubular housing 55 in which the vidicon tube 56 and theintensifier 58 are housed. The vidicon tube 56 has a transparent endplate 57 which is held in flush engagement with a transparent plate 59on the intensifier. The intensifier is held in the housing 55 bythreaded engagement between annular members 60 and 62 which force thesplit ring 63 in engagement with rim 64 on the intensifier. A deflectioncoil 75 and a focus coil 76 are supported in the housing 55 andpositioned about the vidicon tube 56 in a well known manner to providedeflection of the beam thereof. The structure shown in FIG. 4 issuitable for use in a television camera wherein the image is intensifiedand then converted into electrical signals.

The conical beam spring 66 engages the circular edge of button or plate68, which in turn is coupled to the end of the vidicon tube 56 oppositeto the face plate 57. The spring 66 is held in a groove in the housing55, and is supported by a clamping ring 67. The plate 68 has a centeropening 70 for the center projection on the vidicon tube, and openings71 thereabout for receiving the terminals 72 extending from the vidicontube. The spring 66 and plate 68 cooperate to provide a loading of theface plate 57 of the vidicon tube 56 against the plate 59 on theintensifier. This holds the two surfaces in flux engagement and willprovide the desired loading even if the vidicon axis is not precisely inline with the axis of the intensifier.

As previously stated, the plate 68 may be made of plastic insulatingmaterial which has some resilience, such as DELRlN. As illustrated inFIG. 4, the plate 68 is bowed or cupped somewhat by the pressure of thespring fingers of the conical spring 66 against the circular edgethereto. The spring 66 can be constructed of a sheet of beryllium copper0.015 inch thick, and BE- RYLCO 25 manufactured by Beryllium Corporation(Box 1462), Reading, Pa., can be used. In the structure shown in FIG. 4,the outside diameter of the fiat edge of spring 66 may be 2.75 inches,the diameter at the base of the conical fingers 2.25 inches, and theheight of the fingers 0.45 inch above the flat edge. The fingers extendat an angle of 45. The diameter of the plate 68 is l.87 inches and thethickness is 0.04 inch, with the edge or rim having a thickness of 0. l2 inch.

The structure which has been described has been found to provide asubstantially constant load on a shaft or tubular member which findsmany applications. As illustrated, it can be used to hold members infrictional engagement, provide a spring support for a structure, andhold a surface of a device in flush engagement with another device.

claim:

1. A device for applying a substantially fixed axial load to a shaftwhich is subject to movement from a fixed axial position, including incombination,

means for supporting the shaft and permitting limited axial movementthereof,

plate means adapted to be connected to the shaft and extendingsubstantially at right angle thereto, and

spring means including a plurality of symmetrically positioned springfingers forming a concave structure and engaging said plate means, eachof said fingers being resilient and extending at an angle with respectto the plane of said plate means at the point of engagement therewith topermit limited lateral movement of said plate means and apply asubstantially constant load to the shaft.

2. A device in accordance with claim 1 wherein said plate means is adisc having a circular edge, and said spring means is of conicalcantilever beam spring.

3. A device in accordance with claim 2 wherein said plate means isformed of plastic material and said spring means is formed of berylliumcopper.

4. The device of claim 3 wherein said frame means fonns a portion of achassis of an automobile, and said shaft is adapted to be connected tothe suspension of the automobile, with said. spring means and said platemeans forming a resilient support for said chassis.

5. A spring mounting device including in combination,

frame means,

a shaft supported for limited axial movement with respect to said framemeans,

a conical cantilever beam spring having a circular edge secured to saidframe means and resilient spring fingers, and

plate means connected to said shaft and extending at substantially rightangles thereto, said plate means having a circular edge engaging saidspring fingers on the concave side of said spring, with said fingersapplying spring pressure thereagainst.

6. The device of claim 5 wherein said frame includes a gear portion anda clutch portion and said shaft has a flange having a clutch portionadapted to engage said clutch portion of said frame means, with thespring pressure between said spring fingers and said plate means holdingsaid clutch portion of said flange into engagement with said clutchportion of said frame means.

7. A spring mounting device in accordance with claim 5 wherein, saidshaft is a vidicon tube, and said plate means is an insulating resilientbutton having center portion adapted to engage the end of said vidicontube.

8. A spring mounting device in accordance with claim 5 wherein, saidframe means includes a housing having means therein defining a surface,said shaft is a vidicon tube having a surface adapted to be held flushwith said surface within said frame means and an opposite end, and saidplate means is an insulating button having a center portion inengagement with said opposite end of said vidicon tube.

9. The structure of claim 8 wherein said circular edge of said spring issubstantially flat and said spring fingers extend at an angle of theorder of 45 from said edge.

1. A device for applying a substantially fixed axial load to a shaftwhich is subject to movement from a fixed axial position, including incombination, means for supporting the shaft and permitting limited axialmovement thereof, plate means adapted to be connected to the shaft andextending substantially at right angle thereto, and spring meansincluding a plurality of symmetrically positioned spring fingers forminga concave structure and engaging said plate means, each of said fingersbeing resilient and extending at an angle with respect to the plane ofsaid plate means at the point of engagement therewith to permit limitedlateral movement of said plate means and apply a substantially constantload to the shaft.
 2. A device in accordance with claim 1 wherein saidplate means is a disc having a circular edge, and said spring means isof conical cantilever beam spring.
 3. A device in accordance with claim2 wherein said plate means is formed of plastic material and said springmeans is formed of beryllium copper.
 4. The device of claim 3 whereinsaid fraMe means forms a portion of a chassis of an automobile, and saidshaft is adapted to be connected to the suspension of the automobile,with said spring means and said plate means forming a resilient supportfor said chassis.
 5. A spring mounting device including in combination,frame means, a shaft supported for limited axial movement with respectto said frame means, a conical cantilever beam spring having a circularedge secured to said frame means and resilient spring fingers, and platemeans connected to said shaft and extending at substantially rightangles thereto, said plate means having a circular edge engaging saidspring fingers on the concave side of said spring, with said fingersapplying spring pressure thereagainst.
 6. The device of claim 5 whereinsaid frame includes a gear portion and a clutch portion and said shafthas a flange having a clutch portion adapted to engage said clutchportion of said frame means, with the spring pressure between saidspring fingers and said plate means holding said clutch portion of saidflange into engagement with said clutch portion of said frame means. 7.A spring mounting device in accordance with claim 5 wherein, said shaftis a vidicon tube, and said plate means is an insulating resilientbutton having center portion adapted to engage the end of said vidicontube.
 8. A spring mounting device in accordance with claim 5 wherein,said frame means includes a housing having means therein defining asurface, said shaft is a vidicon tube having a surface adapted to beheld flush with said surface within said frame means and an oppositeend, and said plate means is an insulating button having a centerportion in engagement with said opposite end of said vidicon tube. 9.The structure of claim 8 wherein said circular edge of said spring issubstantially flat and said spring fingers extend at an angle of theorder of 45* from said edge.